Each item stored in a user database (feed, mix, recipe, cost...) is internally coded with an alphanumeric string; these system codes are automatically generated by NDS and are unique in each database.
Of course, in different databases the same code could label different items, or vice-versa, the same item (e.g. a certain feed) could be labelled with different codes, since the codes are generated locally in each database.
NDS provides an alternative way to uniquely identify one item stored in a certain database through the so called user ID codes: codes defined by the users that, if properly shared, enforce the data integrity during the exchange of data. Through an auto-coding system, NDS generates these id codes each time a new item is created; these codes can be changed by the user at a later stage, in the case a different scheme of coding was required.
Before running an import you have to choose which kind of codes will rule; in the case of system codes the decision of replacing an existing item, which code matches that of the imported one, is left to the user through an option form that gives a three way choice: replacing, saving the item as a new one (and so keeping the one already in the database) or skipping the import of the item.
When the user chooses an import by user id codes, implicitly he accepts that the user coding in the import file is reliable; the replacements are automatically carried on and no option forms are displayed.
In both cases a back-up of the database before doing the import is recommended practice.
However, there are two situations in which the development of your own user ID codes is not necessary:
- The user works alone with the platform and does not perform any data exchange with other users (closed system);
- The user occasionally exchanges back and forth .nds and/or .farm files but never import or get inside these files. In this case there will be no potential conflict with its own database.
In all other cases we strongly recommend to implement an appropriate and shared user ID code system mainly if you work in a coordinated group of users and if the exchange of data is made on routine basis.